"The reason for this mitzvah is that the [Temple] service requires [proper] intention – kavana – and the garments that are unique to that service arouse one to think in one's heart and imagine in one's intellect the [proper] intent."

This conveys a very important message that is relevant to all of us, all the time. The way we dress has a real impact on our state of mind. The Jewish people are called a ממלכת כהנים – “a kingdom of priests” – for, relative to the world, every Jew is a kohein to Hashem. Therefore we also have unique garments that we wear, such as tzitzit and yarmulke, and we must dress in a respectable and modest manner. By doing so we constantly remind ourselves of our role as Jews.

Rav Menachem Rekanti continues:

וכמו שהלבוש הראו מכבד הגוף, כך הגוף הראו מכבד הנפש, כי הוא לבושה

"And just as the proper garments give honor to the body, so too a proper body gives honor to the soul, for [the body] is [the soul’s] garment."

Just as a person needs clothing to be able to participate in the physical activities of the world, so too the soul needs the body to be able to serve Hashem and perform His commandments. And just as we honor our bodies with proper and clean clothing, so too we should honor our souls with a healthy and clean (morally and physically) body.

The Shelah HaKadosh quotes the Rekanti and says that a person should think about this idea every morning when he gets dressed, in order to motivate himself to properly “dress” his soul as well. By doing this we bring holiness into even the most ordinary activities.